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· Registered
1 Posts
Discussion Starter · #1 ·
Hi All,

I have just joined the forum.

I have recently aquired my TDI and have the sympton of limp mode being activated if the car is pushed hard.

Boost deviation positive (I think that was P01557) is the code currently stored.

My initial inspection revealed a split Brake booster vacum hose which has now been replaced but the problem still exists.
Air filter / fuel filter have been replaced, Air box screen is not present in this car and all vacum hoses and the intake pipe going to the turbo do not appear to be split, although I have not gone so far as to perform a leak test on this. I have not gone so far as to get to the turbo and actuator itself to inspect these yet but, the only other obesrvation I have is that the EGR and housing appear to be new.

I can see from the excellent information on this forum that most likley candidates are a faulty actuator / N75 or sticky VNT on the turbo.

I do have one other clue and that is a distintive turbo noise on deceleration after letting go of the gas at higer rpms. Although its a decreasing noise as the turbo spins down its not consistent, more reciprocating / fluttering.

Has anyone experienced this noise before combined with the error code I have?
Your input would be apreciated.

Dave F

· Premium Member
5,934 Posts
Hi there, I have heard of this noise before but I can't remember where offhand. You're right though with the actuator and N75, the other thing that can cause the overboost is the turbo vanes or waste gate being sticky inside due to carbon build up from the exhaust and possibly a damaged vacuum pipe. Have a look here if you haven't already.


If I find the thing about the strange noise, I'll get back to you.
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